The principal mineralocorticoid hormones (MCH)--aldosterone, deoxycorticosterone (DOC), corticosterone (B)--help regulate body electrolyte composition and blood pressure. Understanding the control of MCH is critical to assessing their role in clinical derangements in these areas, either as causative or contributory in the symptomatology. Certain primary MCH disorders are to be studied: (1) Syndrome of primary aldosteronism. Further classification, characteristics and course will be examined, and the critical data needed for the preoperative distinction between adenoma and hyperplasia defined. The mechanism of the lack of aldosterone suppression by DOC-acetate in primary adrenal disease needs clarification. (2) The 17-hydroxylation deficiency syndrome. Its implications; excessive DOC and B production are to be identified in clinical disorders. (3) Definition of selective primary adrenal hormone deficiency disorders. Secondary MCH disorders are also to be examined: (1) aldosterone deficiency due to renin deficiency--studies to provide for rapid identification and mechanisms of deficiency, (2) The MCH patterns in disorders of ACTH excess and renin excess, (3) The role of subtle enzymatic deficiencies in hypertension which may contribute to specific MCH excesses, (4) The MCH patterns in low-renin hypertension, (5) The study of contrived elevations of plasma renin activity (PRA) in low-PRA states to examine its influence on the MCH and their regulation, (6) The importance of hyperaldosteronism in the hypokalemic syndromes of renal tubular acidosis. Specific areas of MCH control are to be studied: (1) The regulation of acute changes in the plasma MCH. Particular attention will be given the conditions for maximum response. (2) The study of late biosynthetic precursors of aldosterone during ACTH treatment in an effort to define the aldosterone turn-off mechanism of ACTH. (3) DOC control. DOC has dual allegiance: primarily to ACTH but to angiotensin II in ACTH absence. The need for this regulation and its importance in disease states will be defined.